Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Without annotations, the description carries the full burden but only provides the basic action. It does not disclose what 'invert' entails (e.g., does it toggle selection? Does it keep named selections intact? Performance impacts for large selections?). No side effects or state changes are mentioned.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Extremely concise: one sentence for the action, plus an aliases line and an example. Every word serves a purpose. No unnecessary information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a parameterless tool with an output schema (not shown), the description is adequate but could briefly note that the tool modifies the current selection in the viewer. The example is helpful. Slight lack of clarity on whether the selection changes in-place or returns a new selection via output schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has no parameters, so no additional semantics are needed. The input schema is empty and fully covered by the description. The description adds no parameter information, but none is required.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action 'Invert the current selection' with a specific verb and resource. It distinguishes from sibling tools like select_atoms, select_near, and select_chain by specifying inversion rather than direct selection.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this tool versus alternatives. It does not mention prerequisites, context, or scenarios where inversion is appropriate or inappropriate. For example, it does not indicate that a selection must already exist or that inversion toggles the selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.